Precipitator purge circuit



April 1960 R. G. WINKLEIQLECK 2,931,457

PRECIPITATOR PURGE amoun- Filed Sept. 10, 1957 2 Sheets-Sheet 1 rii FIG.

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ROY GORDON WINKLEPLECK INVENTOR ATTORNEY April 5, 1960 R. G. WINKLEPLECK 2,931,457

PRECIPITATOR PURGE CIRCUIT Filed Sept. 10,. 1957 2 Sheets-Sheet 2 T 32 34 r ii ii /20 /0 g 13 23 i I II J- 44/ L FIG?) VOLUME FIG. 4

ROY GORDON WINKLEPLECK INVENTOR ATTORNEY United States Patent r 2,931,451 PRECIPITATOR PURGE CIRCUIT Roy Gordon Winklepleck, Roslyn Heights, N.Y., assigno'r to Apra Precipitator Corporation, New York,

N.Y., a corporation of Delaware Application September 10, 1957, Serial No. 683,113 3 Claims. (Cl. 183-7) The present invention relates to a gas cleaning apparatus utilizing electrostatic precipitators and particularly toan improved system for purging or cleaning particles of solid material from the collecting surfaces of the precipitator.

The purging system of this invention is contemplated for use in connection with electrostatic precipitators of the type disclosed in the Karlsson Patent No. 2,582,133 issued January 8, 1952 in which the gas channels and the electrodes of the precipitator are arranged in sectors or banks each comprising a plurality of channels and electrodes and the prccipitator is continuously cleaned by purging the banks in succession to remove collected particles. In the copending application of Hodson, No. 526,260-filed August 3, 1955, now Patent 2,835,337 dated May 20, 1958 there are disclosed a number of systems in which the collected particles are cleaned from the precipitator by a stream of purging gas that is caused to flow over the collecting surfaces and from which the collected particles are subsequently removed by directing the purge stream through an aftercollector or particle separator of the mechanical cyclone type. The present invention contemplates the employment of purge systems of this type in conjunction with several precipitators whose purge systems may be periodically employed together to effect a more intense cleaning of one of the precipitators.

Figure 1 is a schematic view illustrating the purge system of the present invention in connection with a pair of precipitators and wherein the purge systems of the several precipitators are periodically employed to effect cleaning of one of the precipitators; and

Figure 2 is a graph illustrating the operating conditions with respect to the pressure and volume produced by the cleaning fans; and

Figures 3 and 4 are views familiar to Figure 1 illustrating a system in which a single aftercollector and fan are employed for two precipitators.

In the drawings the numerals and 20 designate a pair of electrostatic precipitators which are interposed in the gas ducts 11 and 21 for electrostatically removing entrained particles of solid material from the gas streams flowing through the ducts. As mentioned above, the particles deposited on the collecting surfaces of the precipitators 10 and 20 are periodically cleaned oil by a stream of purging gas which is drawn over these surfaces by the purge fans 12 and 22. The precipitators 10 and 20 are connected by conduits 13 and 23 to mechanical collectors 14 and 24 which remove collected particles from the streams of purge gas as the latter are drawn through the collectors by the fans 12 and 22 via the ducts 15 and 25. As shown, the fans return the clean purge gas to the systems through ducts 16 and 26 connecting with the raw gas ducts 11 and 21, in which precollectors 17 and 27 are interposed at points in advance of the precipitators 10 and 20. A duct 30, containing a valve means 31 in the form of a damper, interconnects the conduits 13 and 23 downstream of dampers 32 and 34 2,931,457 t n gd Apr- 5, 1960 "ice in these conduits which connect with the related'precipi tators 10 and 20.

Normally each precipitator is cleaned continuously by its own purge system, the fan 12 acting through collector 14 on precipitator 10 while fan 22 purges collector 20. However, to improve efiiciency the invention in-' Damper? P g Normal O1osed Open. Open. High on In Open Open Closed. Highon20 Open Closed Open.

The reason a high purge results when two fans, in parallel, are connected to one precipitator is illustrated in Fig. 2. This shows a typical fan curve I, volume versus pressure and the system resistance curve R. P is the normal operating point. .When the two fans 12 and 22 are paralleled the combined fan curve C, shown in dotted lines, results. The intersection of R and the fan curve, point P gives the operating point for high purge. The resulting purge volume in this case is 20% higher than with the normal damper setting.

Fig. 3 illustrates two electrostatic and mechanical collectors 10, 17 and 20, 27 with a common purge circuit containing aftercollector 44 and fan 42. The damper settings for normal and high purge are shown below:

The reason a high purge can be obtained is shown in Fig. 4. R is the resistance curve for two precipitators in parallel with both valves 32 and 34 open. R is for one precipitator in the purge circuit of fan 42. P is the normal operating point of 50,000 c.f.m. total or 25,000 c.f.m. per precipitator. P is the high purge operating point of 30,000 c.f.m. total flow, but through only one precipitator, thereby giving a 20% increase in purge volume and velocity.

What I claim is:

l. A gas cleaning system comprising: a pair of electrostatic precipitators each acting to collect solid particles from a main gas stream flowing therethrough; fan means associated with said precipitators for causing streams of purging gas to flow over their collecting surfaces to clean collected particles therefrom; a conduit connected to each precipitator for withdrawing streams of purging gas from each precipitator; collecting means for removing said solid particles from the purging gas streams; valve means for each precipitator in the conduit connected thereto adapted when closed to cut off the flow of purging fluid through the precipitator; and a duct connected to said conduit downstream of said valve means placing each precipitator in communication with said collecting means functioning upon the closing of the valve means for either precipitator to cause said fan means to act to purge only 2. A gas cleaning system comprising: a pair of electiostatic @recipitators'feachact-ing to f-collect solid particles from a main gas stream flowing therethrough; n di;

vidual taniassociated with each'preci'pitator {01 2 causing a stream of purging gas to flow over the collecting-sur iacesjof the precipitatorrjfor cleaning collected particles therefrom; acollector for-each precipitate; fort re 'noving said solidparticles from itspurging gas stream; conduits connecting each preoipitator tothe related collector;

other; conduits connecting the related fans to the coliectors {or drawing the streams of -purging gas through fan; a. duct. connecting 7 said firstrmentioned ,conduits to} t gether at points. between each precipitator and the collectorrelatd thereto downstream of said valves and acting-to connect each -precipitator to the collector related to the other .pre'cipitatortand 'valve means inqsaid duct lated fans to the cone prs f dapte w in o n r s l an. tov P eas hqthrqf th fts? when the valve in the first mentioned conduit Connected thereto is open and the valve in the first mentioned con 'du'i't connected to the other precipitator is closed'so as I to isolate it'temp'orarily from its collector and fan.

m ap afnaaipaa trostatic precipitators each lacting to collect solid jarticles from a main gas stream flowing through the respective precipitator; an individual fan associated with each precipitator for causing a stream of purging gastto flow over the collecting surt age s of the precipitator to clean collected particles eaten-em; a collector for each precipitator tor remoying said solid; particles 'from its purging gas stream; conduits connec geach jgrecipitator to the related collector; other eanau comfeeting thei i'etag fthe fs reams iof purging gas through either precipitator, 'itsrelatetlEollec'tor'and fan in series; a duet connecting said first mentioned conduits together at points between each precipi- A. a sleepin yst tator and the collectior'relatfed thereto and acting to con-' nectt each precipitator to the collector related to the other precipitator; valve means in said duct adapted when anv ne ositi nht lac tbttt oi fiaid s a n t n .fiuid ptnmlini pn. ,hnwath J i 9 tsaiqt sttme a slfiqnsis t v n qti it said pesi tat isada ed whe Cl ed q cut fi? Qommum ma between either precipitator and its collector and, fan ind sau eth rm at dv n o st th ough a nn l o and q t t o p r n he o he r tate? 't ar bv in: creasing the flow of purging gas through "said other precipitator, J References Cited in lileof this pate jnt UNITED STA'Tl-ES PATENTS 4 Graemi'ger Sept. 23, 1 924 Hodson Feb. 8, 1955 

